function rd_dss, ra, dec, w, head, node=node

    ; round to nearest 15 arcmin, 1 minute of time
    if keyword_set(node) then begin
        ractr = round(ra * 12.d*60.d/!dpi) * !dpi/(12.d*60.d)
        decctr = round(dec * 180.d*4.d/!dpi) * !dpi/(180.d*4.d)
    endif else begin
        ractr = round(ra * 12.d*3600.d/!dpi) * !dpi/(12.d*3600)
        decctr = round(dec * 180.d*3600.d/!dpi) * !dpi/(180.d*3600.d)
    end

    rastr = rastrf(ractr,0)
    rah = strmid(rastr,0,2)
    ram = strmid(rastr,3,2)
    ras = strmid(rastr,6,2)
    decstr = decstrf(decctr,0)
    decd = strmid(decstr,0,3)
    decm = strmid(decstr,4,2)
    decs = strmid(decstr,7,2)
    
    wstr = string(ceil(w * 180.d*60.d/!dpi),form='(I2.2)')  ; width in arcmin
    
    filename = string(rah+ram+ras,decd+decm+decs, wstr,$
                      form='("~/reference/skychart/dss/dss_",A6,"_",A7,"_",A2,".fits.gz")')

    print, 'rd_dss: ', filename

    if not isfile(filename) then begin
        print, 'rd_dss: accessing DSS to make ', filename
        s = 'curl "'
        s = s + 'archive.stsci.edu/cgi-bin/dss_search?v=poss2ukstu_red&'
        s = s + 'r='+rah+'+'+ram+'+'+ras+'&'
        s = s + 'd='+decd+'+'+decm+'+'+decs+'&'
        s = s + 'e=J2000&'
        s = s + 'h='+wstr+'&'
        s = s + 'w='+wstr+'&'
        s = s + 'f=fits&c=gz&fov=NONE&v3='
        s = s + '" > ' + filename
        
        print, s
        spawn,s
    endif

    print, 'rd_dss: reading ', filename
    d = readfits(filename,head)
    return, d

;    http://archive.stsci.edu/cgi-bin/dss_search?v=poss2ukstu_red&r=18+00+00&d=-20+00+00&e=J2000&h=60&w=60&f=fits&c=none&s=on&fov=NONE&v3=

;    curl "archive.stsci.edu/cgi-bin/dss_search?v=poss2ukstu&r=17+28+55.013&d=-15+00+74.72&e=J2000&h=5&w=5&f=gif&c=none&fov=NONE&v3=" > dss.gif


end